Conventional video tape dubbing apparatus consists of a master VTR (Video Tape Recorder) to send out video signal for dubbing, a distributor to distribute the sent out video signal, and a number of dubbing recorders arranged in parallel to record the distributed video signal. The master VTR sends out video signal of either standard speed, i.e., same-speed, or double-speed signal, and a number of dubbing recorders corresponding to each speed perform dubbing.
Referring now to FIG. 4, the construction of a speed control circuit of a conventional dubbing recorder will be described in the following. In this figure, a frequency modulated video signal, namely, RF signal 1, which is distributed by a master VTR is modulated by a demodulation circuit 4, the output of which is then inputted to a sync separation circuit 5. The control of the recording speed is performed by inputting into a servo circuit 6 the output signal from the sync separation circuit 5 and the output signal from a system control circuit 3, thereby allowing recording of duplicated tapes at the same speed or the double speed. The dubbing apparatus in this arrangement is a dedicated apparatus for each respective speed and is not designed to record by switching a single apparatus between the same speed and double speed.
As an example of a dubbing apparatus, Japanese Laid-open Patent No. Hei 5191,774 discloses a high-speed dubbing apparatus. As this apparatus is a dedicated apparatus for a double speed, there has been a demand from users of the apparatus to allow them to duplicate at the standard speed by switching this same apparatus. When making a double-speed dubbing using the apparatus of this application, it is necessary to prepare 2 identical rolls of master tape. In the case of duplicating tapes in a small lot such as 100 to 5,000 rolls, dubbing at the standard speed will be acceptable, making it unnecessary to adopt double speed and to take the trouble of preparing 2 rolls of master tape. However, when using this apparatus, it is necessary to change dubbing recorder from a double-speed recorder to a same-speed dubbing recorder thereby presenting a cumbersome handling of dubbing recorders. Consequently, with this conventional example, too, there has been a demand for making it possible to switch between double-speed dubbing and same-speed dubbing using a same dubbing recorder and also for making handling of the apparatus easier.